This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 86 |
| 5 | 770 |
| 6 | 5710 |
| 7 | 38626 |
| 8 | 248766 |
| 9 | 1558290 |
| 10 | 9603470 |
| 11 | 58604546 |
| 12 | 355460446 |
| 13 | 2147773810 |
| 14 | 12945690030 |
| 15 | 77907271266 |
| 16 | 468366848126 |
| 17 | 2813865797330 |
| 18 | 16897768573390 |
| 19 | 101444650414786 |
| 20 | 608899287739806 |
| 21 | 3654318951308850 |
| 22 | 21929599650541550 |
| 23 | 131592320786851106 |
| 24 | 789612753560503486 |